The function of NFKBIE (NFKB inhibitor epsilon, ENSG00000146232) is as follows. Sequesters NF-kappa-B transcription factor complexes in the cytoplasm, thereby inhibiting their activity (PubMed:9315679). Sequestered complexes include NFKB1-RELA (p50-p65) and NFKB1-REL (p50- c-Rel) complexes (PubMed:9135156, PubMed:9315679). Limits B-cell activation in response to pathogens, and also plays an important role in B-cell development (By similarity). {ECO:0000250|UniProtKB:O54910, ECO:0000269|PubMed:9135156, ECO:0000269|PubMed:9315679}.